Triacylglycerols are nonpolar, water-insoluble fatty acid triesters of glycerols. Triacylglycerols differ according to the identity and placement of their three fatty acid residues. Lysophosphatidic acid acyltransferase (EC 2.3.1.51), also called 1-acyl-sn-glycerol-3-phosphate acyltransferase, 1-AGP acyltransferase, 1-AGPAT, lysophosphatidic acid transferase, and LPAAT, catalyzes the attachment of the second acyl group to the glycerol backbone during de-novo biosynthesis of triacylglycerols.
The fatty acid distribution in triacylglycerols is thought to be dependent on the spcificities of the acyltransferases involved in their biosynthesis. Although no plant LPAAT has been purified to completion, spinach leaves have at least two systems which reside in different subcellular compartments (chloroplast inner membrane and the endoplasmic reticulum) and which incorporate different fatty acids into the glycerol backbone (Frentzen et al. (1984) in Structure, function and metabolism of plant lipids; Siegenthaler and Eichenberger, eds. pp 105-110). Isolation of LPAAT genes from Limnanthes douglasii is dependent on the approach used to isolate the clone. Two different clones have been isolated which varied in their expression patterns, in their ability to complement an E. coli temperature-sensitive mutant defective in LPAAT activity and in their ability to hybridize to the already known maize LPAAT (Brown et al. (1995) Plant Mol. Biol. 29:267-278). Thus, the presence of many other LPAATs with different specificities, subcellular locations and activities is expected.
Production of industrially-significant oils in seed oil plants has been a quest of the agricultural industry of some time now. Introduction of the yeast LPAAT sequence into Arabidopsis and B. napus results in increased seed oil content in many transgenic plants and in changes in seed oil composition (Zou et al. (1997) Plant Cell 9:909-923).